The present invention relates to a sensor for determining the angular position of a radiating point source in two dimensions and its method of operation. The present invention has particular pertinence in the field of surgery, with particular reference to close range surgical instrument tracking. Additionally, the present invention is applicable in the fields of virtual reality and pilot head tracking systems.
In the prior art, systems have been devised that employ one dimensional masked or coded apertures placed above multi-element one dimensional detectors. Such structure is disclosed in U.S. Pat. Nos. 4,810,870 and 5,408,323. In such systems, correlation techniques are employed to determine the position of a projected pseudo-random pattern on a detector surface by comparing signals from fixed detector elements arranged in a unique pattern or from comparison with fixed reference signals previously stored in a computer.
Additionally, it is known in the prior art to use a two dimensional aperture and a one dimensional detector in the form of a charge coupled device (CCD) to determine angular position in two dimensions. Such a system is disclosed in U.S. Pat. No. 4,092,072. A drawback of such a system is that it does not provide immunity from errors resulting from reflections, and does not yield sufficiently high enough resolution as is the case with techniques employing pseudo-random patterns and correlation techniques.
The prior art systems described above, while capable of determining angle of incidence with high resolution, yield only one-dimensional information. The present invention differs from the teachings of these patents as providing high resolution two-dimensional information. It is with this difference in mind that the present invention was developed.